DE1805007B2 - Use of a mixed polymer resin as a binder in aqueous, electrically cut-off coating compositions - Google Patents

Description

CH ₂ = CR-COOR '

(I)

wherein R is a hydrogen atom or a methyl group and R 'denotes a branched or straight-chain alkyl group having 1 to 18 carbon atoms, and at least one unsaturated monomer that can be polymerized with it,

B. 1.5 to 15 mole percent itaconic or α-methylene glutaric acid and

C. 5 to 50 mole percent of a component consisting of at least one compound with the general formula

= CR - CO - NH - R "OR '" (HI)

consists in which R has the meaning given above has, R "is a branched or straight-chain alkylene group having 1 to 8 carbon atoms and R '"denotes a branched, cyclic or straight-chain alkyl group having 1 to 6 carbon atoms, wherein the sum of components A, B and C is 100 mole percent, the resin after partial neutralization

a) has a pH value in aqueous solution or dispersion which is derived from the equation

pH = pKa + η log

1 -

(IV)

35

for the following values of the resin results: pKa ^ 8; 0.5 g η g 1.5; 0.3 ^ α g 0.8 for η as the apparent degree of neutralization, based on the mol of carboxyl group of the resin,

b) a glass transition temperature Tg of 6O ⁰ C or less and

c) has an average molecular weight of 5000 to 20,000, as a binder in aqueous, electrically depositable coating agents.

2. Use of the partially neutralized copolymer resin according to claim 1 with buckets of additional pigment, the relationship

IpKp - pKa | ^ 0.1

(V)

is sufficient, where pKa has the meaning given above and pKp (negative logarithm the dissociation constant Kp of the pigment) means the acidity of the pigment.

3. Use of the partially neutralized copolymer resin according to claim 1 in an aqueous coating agent which contains 2 to 20 percent by weight of the resin as the main component and which has a specific electrical conductivity of 150 to 800 μ ohms "'cm at 25 ° C and at a solids content of 11 percent by weight " ¹ has.

4. Use of the partially neutralized mixed polymer resin with the addition of epoxy resin and / or N-alkoxymethylated melamine resin containing an alkyl group with 1 to 4 carbon atoms, according to claim 1 or 2.

5. Use of the partially neutralized mixed polymer resin according to claim 1 to 4 in an aqueous bath, used as a means for regulating the Film formation of the resin an amphoteric electrolyte with an isoelectric point of 5.5 to 8.5, preferably an amino acid is added.

In order to give metallic materials good corrosion resistance and a beautiful appearance, asked one previously aqueous or dissolved in organic solvents coating compositions by spraying, rolling, Flowing or immersion applied to the metallic materials. In more recent times have however, electrical deposition and coating processes found attention using aqueous coating compounds, which have the advantage that the films formed are uniform; metal objects with complex shapes can also be used easily coated in this way. There is no risk of fire and no kicking when pulling it over Health problems. Centralized control of the coating levels reduces the Costs possible. Process for the production of coating compositions used in these electrical coating processes are suitable, for example, in U.S. Patent 32 30 162 and in British patents 10 30425, 10 27 813 and 11 15 130. The coating compositions obtained by this process however, have the disadvantage that the contained films are discolored; Coating compounds, in which the films formed do not discolor, are unable to form films that have the anti-rust properties, as required for protective films for metals, with a beautiful appearance and unite an excellent surface gloss. These coatings are therefore mainly used only as primer coats. So until now there was no coating material for the electric Deposition in which the advantages of the electrical deposition process could be exploited and with which at the same time excellent films can be obtained by a single application without a top coat could become.

The compositions known from British patent specification 10 57 723 would be in the form of aqueous dispersions as a coating for electrodeposition because of its poor fluidity when heated unusable.

The usual coating compositions for electrical deposition mostly contain a strong binder water-soluble resins with a large number of dissociating functional groups for implementation electrophoresis and having a large number of hydrophilic functional groups, thereby good adhesion to the materials to be coated is achieved. However, these resins have Disadvantage that bubbles can easily be included in the films obtained; they have a high solubility in water, so that the films formed do not flow well at higher temperatures, making it impossible is to achieve an excellent surface gloss. As a result of their content of highly water-soluble Resins, the films obtained after baking are very sensitive to water and have poor properties

2O

Anti-rust properties. So it was impossible to use these resins as a coating composition for electrodeposition m a single layer. With the aim of the water resistance of the educated To improve films, a coating material has been proposed in British patent specification 1027813, which was obtained in that an acrylamide copolymer which was then treated with paraformaldehyde to form the amide group convert to an N-methylolamide group; in British Patent 1115 130 is a coating material described that by butoxymethylation of part of the N-methylolamide groups a Acrylic coating compound containing an N-methylolatinide group contained, is produced. However, these coating compositions still have a high solubility in water, which is why it is impossible to produce films from these masses by electrodeposition in one layer, which have excellent surface gloss as well as excellent physical and chemical properties Have properties.

According to the USA. Patent 3301822 water-soluble resins by treating polymers containing carboxyl and amide groups with epoxy compounds and formaldehyde. An electrophoretically generated coating from these compositions Due to the properties of the polymers used, it has no gloss and poor water resistance and chemical resistance.

Also with the masses known from French patent specification 14 75 382 for electrophoretic Deposition can not achieve satisfactory results because (as described in the following teaching according to the invention is understandable) no narrow molecular weight range is adhered to.

The masses for electrical equipment known from the Dutch laid-open specification 66 17404 contain a water-soluble alkyd resin, so that the film obtained from these compositions does not get hot is flowable. Also known from the Dutch patent application 65 04 905 for Electro-coating is not satisfactory.

In order to overcome these disadvantages, the inventors made extensive studies; here it was found that it can achieve an electrically in a single layer deposited film, which has both excellent surface gloss and excellent Properties of the thermosetting coating compositions, it is necessary that the number of hydrophilic functional groups in the binder resin component of the coating material is as small as possible, and so small that the resin component can just be dispersed in a stable manner in water to remove the To improve the flow properties of the coating material at elevated temperatures, thereby also the Surface gloss and rust preventive properties of the film formed can be improved.

In contrast, the state known from the Dutch patent application 67 01 343 fails to recognize this in technology the importance of the hydrophilicity of compositions for electrocoating.

In the practice of electrical deposition, a film that is always uniform is achieved it is very important that the bath for the electrical deposition is not subject to any changes over time, In the case of the usual coating compounds, in which a highly water-soluble resin component is used as a binder

35

40

45 , however, the solubility state of the resin component in water changes with time, thereby deteriorating the stability of the electrodeposition and plating bath. Furthermore, the polymerization solvent used in the preparation of the resin solution is generally different from the solvent required for dispersing the resin in water, whereby it is necessary to change the solvents when the resin is dispersed in water. If the polymerization solvent is maintained depending on the solvent exchange method used, or if the H n. Undergoes a change in the dissolved state due to the solvent exchange, the stability of the electrodeposition bath is reduced in some cases. Furthermore, when a pigment-containing coating material is used, the stability of the emulsion is greatly influenced, not only by the properties of the resin used, but also by the properties of the pigment used.

The main purpose of the invention is therefore to create a coating compound (or a coating agent) for electrical deposition, which is stable in an electrical deposition and coating bath and which at the electrodeposition in one layer produces a film with excellent surface gloss and excellent provides physical and chemical properties.

The object underlying the invention is achieved in that one by ammonia or Amine bases partially neutralized copolymer resin

A. 93.5 to 35 mole percent of a component consisting of at least one compound with the general formula

CH ₂ = CR - COOR '

wherein R is a hydrogen atom or a methyl group and R 'is a branched or straight-chain alkyl group with 1 to 18 carbon atoms and at least one unsaturated polymerizable therewith Monomer consists,

B. 1.5 to 15 mole percent itaconic or «-methylene glutaric acid and

C. 5 to 50 mole percent of the component consisting of at least one compound with the general formula

CH, - = CR - CO - NH - R "OR" '

(III)

consists in which R has the meaning given above R "has a branched or straight-chain alkylene group having 1 to 8 carbon atoms and R '" has a branched, cyclic or straight-chain alkyl group having 1 to 6 carbon atoms, where the Sum of components A, B and C is 100 mol percent, the resin after neutralization a) has a pH value in aqueous solution or dispersion which is derived from the equation

pH = pKa + η log

(IV)

for the following values of the resin results:
0.5 | n ^ l, 5; O, 3gagO, 8,

6s b) a glass transition temperature Tg of 6O ⁰ C or less and

c) has an average molecular weight of 5000 to 20,000, as a binder in aqueous, electrical

trisch separable coating agents used Information for α, the apparent degree of neutralization, are ia also in the following) based on moles of carboxyl group.

Another purpose of the invention is to create such an electrodeposition coating agent which has favorable bath stability; to wkd the mixed polymerisation resin according to the invention ! E used together with a pigment that has the! Relationship | jsKp - pKa | ^ 0.1 fulfilled, where pKp the Acidity of the pigment and pKa means the acidity of the resin

The properties of the resin which are necessary for the achievement of the main purpose of the invention are explained below

The resin used in the electrocoating process to create a single final coat is made by taking the properties of the Resin be specifically limited in view of the concern that in the process of making a single layer of earth electrically deposited film is characterized by surface gloss, water resistance and chemical resistance and that the bath for electrodeposition to achieve this excellent properties is not changed during a long period of operation.

An electrodeposited coating made from a resin with high water solubility or are made with a high molecular weight is unsuitable for an electrodeposition process for producing a single final coat due to the poor heat flow properties of the resin.

If the resin is composed of a polymer with a water solubility higher than the Extending wide water solubility range, the electrodeposition bath obtained from this resin lacks the stability to undergo good conditions to be maintained over a longer period of time (cf. Example 2 and Comparative Examples 5, 6 and 7).

The solubility of a resin is determined by the composition and molecular weight of the polymer; therefore the solubility distribution is also influenced by the composition and the molecular weight distribution of the polymer.

The solubility basically depends on the amount of dissociable functional groups. To produce a polymer with low water solubility, a low content of dissociable functional groups must be selected. When poor copolymerizable composite monomers such as acrylic acid or methacrylic acid are used as the acid component in view of a low content of functional groups, the resins produced contain low-acid polymers and high-acid polymers, so that the solubility distribution of the resin with respect to the Qe -Value of the acidic monomer extends over a wide range.

Therefore, in order to avoid the properties listed above, the quality and quantity of the be limited to acidic monomers used. If you follow the interpolymerization process in Towards a lower molecular weight of the polymer leads to a heat flowable resin through To maintain the manufacturing process, the water solubility of the copolymerized polymer increases with a decrease in pKar, which will be explained below; on the other hand, the Proceeding both polymers with and without acid components despite the use of easily copolymerizable acidic monomers, such as itaconic acid or ii-methylene glutaric acid. As a result of this The water solubility distribution of the polymer formed extends over a wide range. That System composed of water and the polymer formed by this method of operation, becomes heterogeneous and shows emulsion behavior and slit in certain cases. The more unfavorable that The selected copolymerizable acidic monomers, the broader the distribution of the solubility of the Polymers.

With the foregoing are the necessary limiting factors for manufacture a suitable resin for electrodeposition processes to produce a single final layer the following: Molecular weight of the polymer, composition of acidic monomers based on the Copolymerizability of the monomer and solubility of the polymer in water. It is clear that the Boundary conditions according to the invention for electrodeposition are suitable for the production of a single final layer, as can be seen from the following examples.

According to the fact that the parameter pKa ic equation (I) becomes smaller and the parameter increases in the same equation through the use of a large amount of hydrophilic functional groups, the solubility of the neutralized water-soluble polymer can be appropriately determined by the pKa value and the η value can be chosen in equation (I) which is defined experimentally.

With regard to the behavior of acidic high polymers in water, it has generally been shown that that in the region where "is not excessively small or large, the following equation holds true:

pH = pKa + η log

1 -

(D

experimentally generally as the relationship of the pH and the degree of neutralization of the water-soluble resin or the water-dispersible resin Resin is obtained (Encyclopedia of Polymer Science and Technology, Vol. 1, p. 218, Inter-Science series), in which pH represents the pH value in aqueous resin solutions or dispersions, pKa represents a parameter that represents the degree of acidity of the Indicates resin component and is defined by the equation

pKa = - log Κα ,

where Ka is the dissociation constant of the resin, and α indicates the apparent degree of neutralization of the resin component, which is determined by the chemical equivalent ratio of added ammonium salt or Amine base is represented to the acid component of the polymeric resin; η represents a parameter which fulfills the above condition.

The value pKa is a characteristic value for the hydrophilic properties of the resin and fluctuates depending on the composition of the resin. For example, with a polymer that picks up a large amount Acid, i.e. a dissociating functional group or a non-dissociating hydrophilic functional group Group contains the value of pKa.

On the other hand, the acid content is kept constant and the content of hydrophilic functional Groups, the value pKa increases. If

IO

a resin is soluble or dispersible in water depends on the values for pKa, η and α, and a resin with a high pKa value or low values for η and α is more easily immersed in water disperse.

To obtain a film with excellent surface gloss and excellent physical and chemical Properties after the electrical deposition and coating process in a single To obtain a layer, the inventors have to take into account the considerations given above examined the useful ranges for pKa, η and α to obtain the following results became.

If a resin component having a low pKa value is used, the obtained electrical The deposition bath is acidic, even if the degree of neutralization of the resin is increased; depending on the type of In some cases, the formation of rust on the metal surface is observed during electrical viewing Deposition process. Furthermore, it has a resin component with a low pKa value a high solubility to water, and the high polymers constituting the resin are with each other blended and are deposited in the blended state on the surface of the metal to be coated. Therefore, the film formed cannot be made flowable again when heated and is not smooth Surface gloss. On the other hand, a resin component having a high pKa value does not get into water dissolved, even if the degree of neutralization of the resin is increased, but merely dispersed. Since the dispersed particles have a tendency to adhere to each other, the film image becomes j η gs by virtue of the resin component decreased during electrodeposition, and the dispersion stability of the resin in the electrical coating bath is impaired. However, as the pKa increases, it becomes fluid of the resin is improved in heat, and the surface gloss of the formed film is increased. According to the invention, the value for pK & at a bath concentration of 11 percent by weight and one Bath temperature of 25 ° C measured.

Of course, if a single layer is electrodeposited, it is necessary to remove the film after Bakeout has useful properties in order to produce a film with excellent surface gloss however, it is necessary that the film formed during electrodeposition be in the Heat runs again. The glass transition temperature is used to form an electrodeposited film Tg of the high molecular substance that is the resin component is an important factor. Will be a Resin component having a high Tg is used, the adhesion of the dispersed particles occurs Coating material difficult so that that formed on the surface of a metal to be coated Film did not have a higher electrical resistance and undesirably decreased its throw is. Furthermore, the film's ability to bleed again on bakeout deteriorates and the glossiness deteriorates of the film obtained can no longer be regarded as satisfactory.

The molecular weight of the resin is also an important one Factor. When a resin having a high molecular weight is used, the same is observed Appearance of using a high Tg resin. Continue not to humiliate yourself only the value for pKa, but the value door η also increases. That's why using a High molecular weight resin is undesirable. The glass transition temperature Tg relates to that of a copolymer with other monomeric units than crosslinking functional ones Monomers and is according to the equation

WTg = WVTg ₁

(Π)

50

55 calculated, where Wi and W _{1 represent} the proportions of the individual monomers which constitute the polymeric component (in percent by weight), it being assumed that the proportion of the polymer with monomers other than crosslinking functional monomers is 100; Tg and Tg ₂ denote the glass transition temperatures of the homopolymers from the individual monomers which constitute the polymer.

Furthermore, the molecular weight is an average molecular weight determined by the method osmotic pressure was calculated. The molecular weight range, which is suitable for a coating is between 5000 and 20,000. If the molecular weight is lower than 5000, the dispersibility of the polymer is undesirably low; is this Molecular weight higher than 20,000, the lower the pKa of the polymer and its properties in electrodeposition are undesirably degraded.

Thus, the necessary conditions for obtaining a film with excellent surface gloss and excellent film properties after the electrodeposition and coating process in one layer are such that the high polymer in the coating composition used has the following properties: a pKa value of at least 8.0, a parameter η from 0.5 to 1.5, a degree of neutralization α from 0.3 to 0.8. a glass transition temperature Tg of 60 ° C or less and an average molecular weight of 20,000 or less. Especially if the bath stability is to be guaranteed to a sufficient extent, it is necessary that the bath as the main component is 2 to 20 percent by weight of a resin with a pKa value of 8.5 to 9.5. an? i value of 0.8 to 1.3, a Tg value of 30 ⁰ C or below, preferably from -25 to 10 ⁰ C and an average molecular weight of 15,000 or less and that, if the solids content of the Bath is 11 percent by weight, the specific electrical conductivity of the bath should be 150 to 800 μ Ohm 'cm " ¹ (measured at 25 ^C C).

A coating material for electrical deposition, which is composed of a water-soluble or water-dispersible resin which is the Above, fulfilled the specified conditions, has excellent properties even when applied in one layer. In order to obtain the resin component satisfying these conditions, the following are the Monomers that make up this resin investigated.

In general, monomers with crosslinking functional groups have thermosetting properties usually have high polarity and strong hydrophilic properties. To an electrically separated Film with the desired solvent resistance. Stain resistance and the desired To obtain rust protection properties, one should use the

»9537/397

Increase the crosslink density of the film. To this nyl-, decyl- dodecvl- or

_m : re1n1Lm.1ShohAf f ^ f * "T mere m fairly high proportions are used.

However, polymers obtained using large amounts of these hydrophilic vinyl monomers have a low pKa and a high value, and therefore they are undesirable. In order to take into account the above-mentioned stability of the coating bath, it is expedient to use a long-chain alkyl acrylate or S acrylate and a short-chain iGkytaSatodS- _{meth acr} Jl _at in the appropriate combination. The other rnischZCSb i

saturated monomers ?! Styrene I S

Eh!

whereby polymers with values for pKa, n, Tg and

an average molecular weight within the ranges given above are obtained, which result in suitable crosslinking densities. In general mine have hydrophobic crosslinking functional ' Groups have a relatively low reactivity in networking; however, they have the advantage that they flow again when heated before the crosslinking reaction begins, so that smooth over- *> Drawn surfaces can be formed.

The inventors now have resin? examined which satisfy the purposes of the present invention. It has been found here that the> ₅ purposes of the invention can be achieved by using a mixed polymer as a coating resin, which has the following composition: 93 5 to 35 mol percent of a component A, which is a monomer mixture of at least one monomer with the general formula

CH ₂ = C - COO - R "- OH

I.
R.

(VI)

d oxySoS
ätS or i

■ L

tion dS ■ & ? T ',,

Ko ^ onentXgS ElH Zf " Fi h ^

^Polvmerisa -

if
T

CH ₂ = C-COOR

"FormeHIl" ^de . ^{M. Monomers} ™ ". ^The " ™ " ^sleeve '" ^{and the} other "ji-athyunsaturated monomers 99.9: 0.1 to 40:60

mn

wherein R is a hydrogen atom or a methyl group and R 'is a branched or straight chain alkylene with 1 to 18 carbon atoms, and at least represents another unsaturated monomer copolymerizable therewith: 1.5 to 15MoI-

Percent of a component B, which is a compound with the general formula ^g

CH, = C - COOH

(CH) COOH ^{( ) m H.}

_(IV1

wherein m represents 1 or 2 ; and 5 to 50 mol percent of a component C. the at least one compound having the general formula

CH ₂ = C - CO - N (V,

I \ «ν»

R R '- OR

where in R the meaning given above, R "has a branched or straight-chain alkylene group to with 1 to 8 carbon atoms and R "is a branched one represents cyclic or straight-chain alkyl group having 1 to 6 carbon atoms

The compound used in this invention m, t of the general formula III is an acrylate or meth acrylate 6 _S. in which the alkyl group represented by R 'is methyl, ethyl. n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, peniyl, 2-ethylhexyl, No- " ■ α ν ^l " ^{n carbon} acids of the formula IV can! ^{n _p Kom} ° P component B also acrylic, methacrylic, crotonic, fumaric and maleic acids or anhydrides of these

"Yoke sSSi'nrfϊ ™" ° J ^{eSe acid "Lasse" Si} ° ^h η upper ΞΓηηΓ ^{"other used Mo"} dSiSeTÄ'S "" ⁰¹ · ^{why the EXP} f "elekfriSen AbscheHnn ^V ° ^rgeZOgt -l ^ ill. The bc of must Ί Ie I? H _R ^{8 v} | ^rw endel polymers

£ Se Ξη ΐι I ■ ^ ^{structure habcn} · ^{in particular} "STnPd ^ 8 ^leichm permeable pKa. Using polymers not mn a broad pKa distribution, the polymer migrate with a low pKa ^mitder 2 ^eitin the aqueous phase, whereby affecting only the stability of the coating bath ^{sO n au countries, ch} d'e properties of the films formed ScS M s ^{S "therefore} ί ^required - ^Ilac0"..??? -

himself ^ aSgeze'idJni! "ίΓ ^{TO use} - ^the

ΠίΓΞ wl ? let nuschpolymenaeren.

The acids mentioned above do not stand out

only essential «, in order to understand the components of the

Oberzugsmatcr.ais elektrop _n Oret _IS che properties

noticed fi'irdi ^ ΐ? * ™ *** ^{"3Uch unabd} ingbare EIemcnte door DispergKrung the components of Oberzugsmaterials in an aqueous medium. Räk ^a rg ^Ch λ ^S K '· ^1' '·« «« «for Vernetzun ^ sverbcsserT '^ Z ^ ** ^Films ^ ** ¹¹ * Continue the affinity ^ ΓρίΞΤ ^ ¹¹ ' ^ ^ ¹ * ™? ⁵ ™ ¹⁸⁸ « ¹ nnncnt η n.7" f ^ ¹ "! ^ ^more the Harzkomjed? ih hvdronJ »^^ ^an ^ ^flat acids are in ^ siwfvl compounds, so that they. If you

schEdSir aü * ZL Γ ** ¹¹ ^ ^WCTden · ^{CinC Vcr} "kalSn" EL «1, « ί T " ^{1 Har? es and the} ****" kenMF, i, a I ίκ ™ ^the ? ^cbildctc "F« mc bewir-L »i therefore necessary to use these acids only in

^{up to 15 ml}

": _ij _t J.« «>

An important feature of the invention resides in the use of the compounds with the general Formula V. Typical compounds are acrylamides or methacrylamides, in their N-alkoxyalkyl group the N-alkoxy group R '"O - a methoxy, ethoxy, butoxy, n-propoxy, pentoxy or

H / - group

represents and the alkylene group - R "is a methylene, Means ethylene, propylene, hexylene or 2-ethylhexylene group. These connections are stronger hydrophobic crosslinking functional monomers as the acrylamides, methacrylamides and N-methylolacrylamides or methacrylamides and can be used in relatively large amounts, without the pKa value and the η-Wei t of the polymers formed being impaired. Continue to deliver they films that not only have the desired crosslink density, but also work well in the warm run, whereby glossy coated surfaces can be obtained. Of these monomers are N-butoxymethyl acrylamide and N-butoxymethyl methacrylamide particularly preferred comonomers. because they are not only excellent with the others Let the monomers polymerize and the bathed Polymers have good storage stability, but also have a high affinity for them Pigments, mclamine resins and epoxy resins that can be combined with them. The quantities of this Monomers are in the range from 5 to 50 mol percent, preferably between 10 and 30 mol percent, if one takes into account the values for pKa and π in the polymers formed.

The monomers indicated above can be used to prepare the polymers suitable according to the invention in a manner known per se in a common organic solvent in the presence of the desired Amounts of a free radical polymerization catalyst and a modifier for the molecular weight are polymerized. But if you take into account the stability of a dispersion of the formed polymers in water and the Stahl.tat des aqueous bath as time progresses, so is the use of organic solvents that are miscible with water, particularly desirable. Such organic solvents are, for example Alcohols such as methanol, ethanol. Butanol. Propanol and isopropinoi; Glycols such as ethylene glycol, Propylene glycol. Hexylene glycol and diethylene glycol; Ethylene glycol monoallyl ethers such as methyl, ethyl and butyl ethers: or aqueous mixtures of these Solvent. The great »advantages that come with the help of the polymerization solvents specified above are shown below.

When dispersing a polymer in water it is not necessary to change the solvent, as is the case with a water-insoluble Hches Polymerization solvent was used. Furthermore, after the solvent exchange, the Polymers formed themselves generally have pKa values in a certain range, i.e. a polymer with eihv.Ti has a low pKa value. in the to migrate aqueous phase. Accordingly, the stability of the in a resin solution is lowered polymers present during storage. Will dage_ τι a? 'it water miscible organic When solvents are used, there is no such solvent exchange when the polymer is dispersed in water necessary. Furthermore, the polymer is in the organic solvent, which is why there is the dissolved state of the polymer does not change; In this way, a coating for the electrical Deposition with excellent stability can be obtained.

All customary free-radical polymerization initiators can be used in the preparation of the polymer will. Examples of such polymerization initiators are benzoyl peroxide, cumene hydroperoxide, di-tert-butyl peroxide, azobisisobutyronitrile and azobisisovaleronitrile. As a modifier for the molecular weight, mercaptans such as tert-dodecyl mercaptan, n-dodecyl mercaptan and butyl mercaptan can be used or 2-mercaptoethanol. be used.

In order to disperse the copolymer formed in water, it must be neutralized. Suitable Neutralizing agents are ammonia, primary amines, secondary amines, tertiary amines, hydroxyalkylamines ode »· their size. These neutralizers however, have adverse effects on the pKa and η of the polymers depending on the extent

depend on their hydrophilic properties, which is why they should be used with caution.

To prepare the N-alkoxyalkylamide copolymers given above, it is possible to start from isolated N-alkoxyalkylacrylamides or methate-rylamides. In addition, so-called polymer modification processes are described in USA.-Palentschrift 28 70 611 and in British Patent 11 15 130, according to which Interpolymert with amide groups or N-methylolamide groups using acrylamides, methacrylamides, N-methylolaerylamides or N-methylolmethacrylamides as comonomers and subsequent N-alkoxyalkylation of the amide groups by aldehydes and alcohols. In these processes for modifying the polymers, however, there is the possibility of hydrophilic groups remaining behind. Furthermore, the solvents used are water-insoluble organic solvents, which is why the polymer solutions formed should be subjected to a solvent exchange, which, however, results in a disadvantageous flow. the door values pKa and η of the polymers hai. Furthermore, the polymers run poorly when heated, and the electrodeposition baths have a lower bath stability. According to the above-mentioned methods, therefore, the present electrodeposition coating compositions in a layer which are excellent in film formability cannot be obtained. Furthermore, when using this process, it is necessary to add acidic catalysts in order to completely N-alkoxylate the amide groups or the n-methylol amide groups in the polymers. These acidic catalysts have a detrimental influx during the electrodeposition, which is why it is impossible by these processes. Coating compounds for electrical deposition; in the form of a single coating. Accordingly, it is necessary to use an N-alkoxyalkylacrylamide or methacrylamide al comonomer to achieve a coating material for electrical deposition. In this case, however, the great difficulty arises. that the isolated N-alkoxyalkyldcrylamide or methacrylamide is expensive.

It is therefore advisable to use the processes described in DT-OS 1817 867, cheaper N-alkoxyalkylacrylamides find to use methacrylamides as comonomers.

In one of the methods, an N-alkylol acrylamide or methacrylamide is used as the starting material; a mixture of a lower aliphatic alcohol and an organic solvent which forms an azeotrope with water or a vinyl monomer which forms an azeotrope with water is used as a dehydrating agent; the unsaturated acid (B), which is an essential part of the present composition, is used as a catalyst for the N-alkoxyalkylation of the N-alkylol group.

A second method uses acrylamide or methacrylamide as the starting material; a mixture or addition product of formaldehyde and a lower aliphatic alcohol is used as a modifier for the amide group; finally, the same dehydrogenating agent and catalyst are used as in the first process. According to the two methods, a monomer mixture containing the component C and the component B can be easily obtained.

The present coating compositions for electrical deposition crosslink by themselves and produce films with excellent physical properties. However, in order to improve the properties of the films formed, z. To further improve hardness, corrosion resistance and the like, it is desirable. Melamine resins or add epoxy resins. Suitable melamine resins are preferably N-alkoxymethylmelamines those in which the alkyl group of the alkoxymethyl group contains 1 to 4 carbon atoms. Besides you can also use N-alkoxymethylmeiamines in which the N-alkylol group is still partially is available. Suitable epoxy resins are those with an epoxy equivalent of 100 to 2000. For this purpose include, for example, condensation products of polyethylene glycol or polypropylene glycol with epichlorohydrin; Triglycidyl isocyanurate; Epoxy resins obtained from epichlorohydrin and bisphenol-A; epoxidized resins; Vinyl cyclohexene dioxide; Diglycidyl phthalate ester: and glycerol triglycidyl ether.

These epoxy resins have a beneficial effect, in particular because they improve the corrosion resistance of the films formed. Furthermore, these compounds are usually used in the form of solutions in suitable solvents; but they can also be used in the form of powders.

In order to disperse the polymer obtained in the manner indicated above in an aqueous medium and to use the dispersion as a bath for electrodeposition, the specific electrical conductivity of the bath at the time of manufacture should be about 150 to 800 μ ohms "'cm" (for a solids content of 11 percent by weight and a bath temperature of 25'C). If the specific electrical conductivity of the bath is higher than 800 μ Ohm 'cm', the efficiency of the electrical deposition of the components of the cover material on the surface is reduced If the specific electrical conductivity is less than 150 µ ohm " ¹ cm" ¹ , the amount of particles of the coating material applied to the metal surface increases, but the degree of deposition of the particles of the coating material on the surface to be coated decreases , whereby the adhesion between the gebilde th film and the to be coated Material is reduced in an undesirable manner and the solvent remains in the film. It is therefore he wishes that the specific electrical conductivity of the deposition bath is set to about 200 to 600 μ ohms "'cm" ¹ .

One according to the usual polymerization process

ίο obtained polymer is a mass of polymer with a relatively wide range of scatter, the values for pKa, η and the molecular weight. Wire is therefore a common coating material. which contains such a polymer is used to prepare an electrodeposition bath, so over time the polymers with a low pKa migrate into the aqueous phase, whereby the apparent pH of the whole system in the coating bac decreases, the specific electrical conductivity of the bath increases and at the same time approach a certain value. Furthermore, the dissolved state of the particles in the coating material changes, the differences in the electrophoretic migration of the particles are absent, and deposits are formed.

hit. As a result of this change in the coating bath over time, the gloss of the deteriorates formed film undesirably and its physical properties deteriorate as a result increasing film thickness.

With the electrodeposition coating material according to the invention, the above-mentioned undesirable phenomena can now be overcome. However, it also occurs with an electrodeposition bath. prepared using the present coating material containing the polymer obtained under the severe conditions set forth above poses the problem. that the pH of the bath decreases and its electrical conductivity increases when it is left to stand for a long time after preparation, with the result that the resulting film has inferior gloss and physical properties. These problems are likely due to the fact that the water-soluble polymers with a low pKa orient themselves and migrate into the aqueous phase, as described above. Are these water-soluble polymers, which have migrated into the aqueous phase, by dialysis or with the aid of ion exchange compounds, e.g. B. ion exchange resins or ion exchange membranes, removed from the bath, the pH and the specific electrical conductivity of the bath can essentially return to the same respective values.

as they existed in the manufacture of the bath, are brought back, reducing the shine and the physical properties of the films formed can be kept constant. In addition to stabilizing the electrical

Separating bath by ion exchange compounds there is a method in which an amphoteric electrolyte is in the vicinity of the pole of a to be coated Material can react as a base, is added to the deposition bath, thereby increasing the stability of the bath

6s can be improved a lot. The in this procedure appearing phenomena have not yet been clarified in detail, but it is assumed that they refer to a weak separation of the particles of the coating

materials near the pole are to be returned. Such amphoteric electrolytes are preferably used with an isoelectric point from 6.5 to 8.5, e.g. amino acids such as L-histidine, L-glycine etc. be improved in that the particles of the coating material are prevented from settling in the aqueous medium to agglomerate or that a nonionic surface-active agent is added to the coating bath, which prevents leaching of the polymers with a low pKa value into the aqueous medium A copolymer of ethylene oxide, for example, can be used as a nonionic surface-active agent and propylene oxide can be used. If the film formed is to guarantee good rust protection, so an alkylamine, preferably a water-insoluble alkylamine, the contained in the polymer Acid group can be added during the curing of the film. As water-insoluble Alkylamines are used, for example, n-butylamine, n-hexylamine, n-octylamine and laurylamine.

Coating compounds for electrical deposition, which contain pigments have hitherto been obtained from a pigmented paste, "those obtained by neutralization of a cover material in order to increase the dispersibility in water, adding a pigment to the topcoat material and then kneading the formed mixture was produced. The coating compositions for electrical deposition produced in this way however, have different stability in an aqueous bath. Furthermore, upper pull masses were used with an excellent dispersion stability until now only obtained by random trial and error, and Methods for analyzing and determining the causes for these different bath stability have not yet been found.

Taking this actual condition into account, the inventors have made investigations, particular attention has been paid to using a pigmented paste material excellent properties, which are suitable for a coating in one layer, only then obtained if the properties of the pigments used are also taken into account, no matter what, 4s how good the resins already developed for a coating were in one shift. It has been found that a pigmented coating material for electrical Deposition with excellent properties suitable as a coating in a layer is thereby obtained can be used if a resin is used which, after neutralization, has the following properties has: 8.0 S pKa. 0.5 £ n: £ 1.5 and 0.3 S α ^ 0.8 (cf. formula I), and if a pigment is used which has the relationship ss

between the resin and the pigment according to the following formula:

P [H ₂ O] + RCOOH -

P [H, O®HPOOCR (VIII)

wherein P [H ₂ O] is a pigment with adsorbed water and RCOOH is a resin with carboxyl groups. The dispersion stability of the once coated pigment in water is greatly influenced by the properties of the resin used. It is assumed that K ₁ in formula VIII is proportional to the value of IpKp - pKa | that is, the difference between pKa, which represents the solubility of the protons of the carboxylic acid resin, and pKp, which represents the proton donating power of P [H ₂ O]. The greater the value for IpKp - pKa | the more firmly the pigment is coated with the resin, and the dispersibility of the coated pigment is comparable to that of a resin without pigment, so that here too the effect of a resin suitable for forming a single-layer coating with excellent values for pKa and η comes into play.

If a pigment and a resin are used in such a way that the relationship pKp ^^ - pKa is satisfied, the wetting according to the formula VIII between the pigment and the resin becomes markedly smaller, and the dispersibility of the pigment itself in water is also inhibited. Therefore, it is considered that the formed aqueous bath has lower dispersion stability and, at the same time, the pigment and the resin have different electrodeposition behavior, with the result that the properties of the formed film are also inferior. In order to obtain a pigmented coating material with excellent dispersion stability in water, which is suitable for single-layer coatings, it is necessary that the conditions IpKp-pKa | ^ 0.1 is fulfilled.
The value for pKa is measured as follows:
A water-insoluble pigment is amphoteric and, when it is dispersed in an alkaline or acidic medium, shows excellent dispersibility, whereas at an approximately neutral pH the dispersibility drops significantly. In a dispersion with an alkaline pH, the pigment is negatively charged and the pH value decreases with increasing pigment concentration. So OH "groups are adsorbed on the pigment surface and the pigment is dispersed according to the following equilibrium:

K,

P (H ₂ O) -

P (OH) + H ⁺ (IX)

IpKp - pKa | £ 0.1

(VII)

where pKp is the acidity of the pigment and pKa is the acidity of the resin.

The dispersion stability of a coating material in an aqueous bath containing a pigment and a resin contains is greatly influenced by the wettability between the resin and the pigment. According to the invention the pigment is coated with the resin in an organic solvent, and the wetting process is believed to be where P is the pigment. As the dispersibility of the pigment increases with increasing P (OH "), the equation applies

K ₂ = [P (OH-)] [H ⁺ MP (H ₂ O)].
Thus becomes

IMO pe,

IMO-.

18 05 0G7 ήθ

18th

reached a certain value

WirdpK ₂ durchpKpersetzt, _S oistesaufGrundder water _Kondensa tion reaction considered.

,, FP (OH) yes as ^CB "* -rr: The product was gas chromatographed

ih esche the expression log -j ^^ ÖfT 'The ^ ^b £ ^d ^ S ^ became that the acrylic-

lid

That

Relationship between the expression log
which represents the dispersibility of the pigment, and the pH of the aqueous bath possible to define pKp by the pH at the time at which the pigment begins to disperse on the alkaline side. If the pH value is measured at this point in time, the value for pKp can be calculated.

According to the invention, the usual inorganic pigments such as titanium oxide, Iron oxide red, carbon black, cobalt blue, ultramarine blue, a green pigment from basic copper acetate, manganese blue, a purple pigment made from basic carbonate and barium sulfate, chromium oxide, cobalt-chrome green, Iron oxide yellow, cadmium yellow and barite, as well as common organic pigments such as red and yellow Azo and toluidine pigments and phthalocyanine blue. In addition, all pigments can be used that are only sparingly soluble in water. The pigments should, however, be chosen so that the relationship IpKp - pKa | ^ 0.1 is fulfilled.

The present coating compositions for electrical deposition ■ can, if they are clear or colored Varnishes are applied, not just films with excellent physical and chemical properties result, but also films with white and light, clear colors and excellent surface gloss. 30 nawu »». - -

The coating can be carried out in such a way that the electrical monomers specified are obtained. Deposition is usually carried out at voltages of about 40 to 200 V, whereupon the film formed is washed with water, dried and then baked for about 30 minutes at about 140 to 250 ⁰ C

965% in N-butoxymethyl vice had 2,500 parts of this product would _mL t 1,055 parts of isopropanol mixed, followed KB5Tcüe an azeotropic mixture of benzene and isopropanol were distilled off.

B The monomers indicated below -vur- J »£ filled the flask used in A, wöbe a monomer mixture of N-butoxymethyl-SySmId and itaconic acid in the same manner as obtained from A.

N-methylolacrylamide ^ 32 parts

n-butanol 703 parts

Benzene. 162.5 parts

iSSnonmonomethylether ... 3.S 1 ,, Ic

Gas chromatographic analysis showed that the , ndlune from N-methylolacrylamide to N-but- "crvlamid 97.5%. 2500 parts of this were verBenzene with isopropanol as azeo- > nes vjcimoch distilled off. .

C iT the same way as be. A became a A mixture of N-butoxymethylacrylamide, and acrylonitrile from the below

Aci ylamid

40% formaldehyde solution

in butanol

Acrylonitrile

Itaconic acid

Hydroquinone monomethyl ether n-butanol

444 pieces

The coating compositions are particularly valuable in the case of chemically treated, cold-rolled steel plates, on which it has previously been very difficult to apply films with excellent surface gloss and excellent physical properties by electrical deposition in one layer; With the help of the coating compounds, such excellent films can now be applied to the cold-rolled steel plates . must be brought "- · ₆ " ~ —— a mixture of n-butoxymethylacrylamide monomers

The compounds to be used according to the invention '"" - * """ ^A ™ " »^« tPhmd an-

Gas chromatographic analysis of the product indicated a conversion of acrylamide to N-butoxymethylacrylamide of 96.0%. ....

D In the same way as for A, a

are explained below using examples in which all parts and percentages are given refer to the weight.

Production of a monomer mixture from N-butoxymethylacrylamide and itaconic acid

5 ° and: rMethylene glutaric acid from those given below Obtain monomers.

Acrylamide

40% formaldehyde solution
inButanol 538 Part e

? SSE

he:::

uenzoi. _{8n T.} ,

a-Methylenglutaric Acid 180 I hurry

Hydroquinone monomethyl ether ... 3.5 leiie

A. The monomers listed below were placed in a three-necked flask equipped with a stirrer, separator 55 " ^J

and thermometer, and the mixture was. Gas chromatographic analysis of the sample under dehydration for 6 hours at 70 to 97 ⁰ C was a degree of conversion of acrylamide

to N-butoxymethylacrylamide of 95.5%. The test results given below A to D are sufficient to explain the invention. These results are in the respective Comparative examples given.

decanted.

Acrylamide 444 parts

n-butanol 760 parts

Benzene 700 parts

Itaconic acid 162.5 parts

40% formaldehyde solution

in butanol 538 parts

Hydroquinone monomethyl ether ... 3.5 parts

65

example 1

njunMiiiiw ...,. j-jj _{e after the} connections specified were

The separator was first filled with benzene, the one in a four-necked flask with stirrer, thermometer and the time after which the amount of draining and cooler was poured in, and the mixture was in

18th

your nitrogen atmosphere for 6 hours at 68 ° C and then polymerized at 75 ° C. for 2 hours.

Ethyl Acrylate 271 parts

Styrene 166 parts

N-butoxymethylacrylamide 100 parts

Itaconic acid 12.4 parts

2-mercaptoethanol 5.8 parts

Azobisisobutyronitrile 24 parts

Isopropanol 427 parts

The resulting copolymer solution was neutralized by adding 6.65 parts of j3-dimethylaminoethanol, a resin solution having a solids content of 57.2 percent by weight, an acid number of 9.8, a glass transition temperature Tg of 15 ° C., a pKa of 8.7, an η value of 0.9, an average molecular weight of 8.5-10 ³ and an α value of 0.45. To 100 parts of this resin solution, 75 parts of titanium oxide having a pKp of 9.53 were added, and the mixture was milled in a ball mill for 24 hours. The mixture was admixed with another 200 parts of resin solution and ground again for 24 hours, a white, pigmented paste being obtained. This enamel paint was used to produce an electrical deposition bath with a solids concentration of 12.8 percent by weight, a pH of 8.42, a specific electrical conductivity of 1.75 · ΙΟ ² μΟΙππ ^ αη " ¹ (measured at 25 ° C and a solids content of 11%; the same applies also used for after) using the thus helge presented öberzugsbades were a cold rolled steel plate, a zinc phosphate-treated steel plate and treated with ferric phosphate soft steel plate at a bath temperature of 25 ⁰ C for 3 minutes at 60 V (electrode spacing. = 40 mm; ratio of cathode area to anode area = 5/7) After washing with water and drying in air, the films obtained were baked for ^{30 minutes at 180 °} C. The properties of the films obtained are given in Table I.

007

Table I.

properties Substrate with Ferri with zinc cold phosphate phosphate rolled behan behan stole delte delte plate stole stole plate plate 89.1 86.9 Glan ^ ert (60 °) 90.5 26th 29 Thickness (μ) 28 2H 2 H Pencil hardness 2H 100 100 100/100 Cross cut 100/100 Resistant to solvents speed 4th 4th Xylene 4th 4th 4th Isopropanol 4-5 5 5 acetone 5 5 5 Alkali resistance 5 5 5 Acid resistance 5

The gloss value was determined using the 60 ° mirror surface reflection method measured.

The cross-cut value was determined to leave 1 mm squares with a needle on the film surface were scratched, which were peeled off with an adhesive tape; the number of those left behind Squares are given in percentages.

The solvent resistance was determined so that the film surface of the coated plate was 20 times rubbed with a cheesecloth soaked in an organic solvent and the extent of damage the film surface according to the 5-note system was evaluated. The best value was given a grade of 5 and the worst value a grade of 1 designated.

The alkali resistance was determined so that a spot of a 5% aqueous sodium hydroxide solution Put on the film surface of the coated plate for 24 hours and determine the extent of damage of the film evaluated according to a 5-note system became.

The acid resistance was determined to be a spot of a 5% hydrochloric acid aqueous solution on the film surface of the coated The plate was brought in and the extent of the damage was evaluated using a five-grade system became.

The substrate was a cold rolled steel plate with dimensions 70 150 χ 0.8 mm which was either used as such or after treatment with a rust preventive agent.

The results of Table I show that those formed using the present coating composition Films not only have excellent gloss but also have other excellent properties and that the coating compositions according to the invention are suitable for a single-layer coating.

Example 2

The compounds listed below were placed in the same vessel as in Example 1, and the mixture was polymerized for 12 hours in the same manner as in Example 1, whereby a Resin solution was obtained.

2-ethylhexyl acrylate 806 parts

Styrene 520 parts

N-butoxymethylacrylamide-itaconic acid mixture (B) 965 parts

Itaconic acid 16.5 parts

Azobisisobutyronitrile 59.0 parts

2-mercaptoethanol 22.5 parts

Isopropanol 763 parts

44.4 parts of i-dimethylaminoethanol were added to the resin solution obtained in this way, a resin having the following properties being obtained: Tg = -9 ° CpKa = 9.20, (i = 1.17, average molecular weight 9.6. 10 ³ , a = 0.4, 100 parts of this resin solution were admixed with 75 parts of titanium dioxide (pKp = 9.06) and the mixture was ground in a ball mill for 24 hours the whole was ground to give a white, pigmented paste. This enamel paste was used to make an electrodeposition bath with a solids concentration of 13%,

a pH of 9.02 and a specific electrical conductivity of 2 ^ 4 · ΙΟ ² μΟητη ^ αη " ¹ properties (at a solids content of 11%) were used. Using the coating bath thus prepared, a cold-rolled steel plate, one with zinc phosphate treated steel plate and a ferric phosphate treated steel plate individually in an electrodeposition bath at a Bcd temperature of 25 ° C for 3 minutes at 80 V under the same,

Electrode conditions treated as in Example 2. io öiegeveisucn After washing with water and drying in air, the films obtained were baked out at 180 ^° C. for 30 minutes. The properties of the films so produced are given in Table II.

Substrate

cold rolled steel plate

with ferric phosphate with zinc phosphate treated delte Steel suhl plate plate

Salt spray test

2 mm - -

12.5mm 12.5mm 3.5mm

Table II

Substrate

cold rolled steel plate

steel plate treated with ferric phosphate

zinc phosphate treated steel plate

Gloss value 86.3 86.5

Thickness (µ) 38.0 41.0

Pencil hardness F-H F-H

Cross cut 100/100 100 100 solvent resistance

Xylene 5 5-4

Isopropanol 5 5

Acetone 5 5

Alkali resistance 5 5

Acid resistance 5–4 5–4

Erichsen value (mm) 9.0 8.1 Impact strength (cm)> 50> 50

84.3 34.6 F-H 100 100

5-4

5-4

7.7

> 50

20 In table II the other properties besides the impact strength, the bending test and the salt

, «Fog test the same as in Table I.

The impact strength was determined so that a Iron hammer with a diameter of about 13 mm and a weight of 500 g vertically a certain height fall on the surface of the film Ssen was; the impact strength of the film .st expressed as the height of fall of the hammer at which the Film surface is damaged.

The bending test was carried out in such a way that a steel rod with a diameter of χ mm was attached to the back of the coated steel sheet and the steel plate was bent through an angle of 360 °. The result of the bending test was expressed by the diameter of the steel rod at which damage to the film surface was intnt. The salt spray test was carried out in such a way that the film was incised linearly and sprayed for 48 hours with a 5% strength aqueous sodium chloride solution at 40 ° C., after which the incised part was peeled off with the aid of an adhesive tape. The result

nis of the salt mist or salt spray test was taken as the width of the peeled film at the time of Peeled off. .

The changes over time in the above Coating baths obtained in this manner

observed on the basis of the gloss values of the films formed The results are given in Table III.

3 °

Table III

Substrate

Days 0

84.1

81.8

. . 73.5

Specific conductivity (μ ohms " ^l cm ~ ¹ ) 2.24

Cold rolled steel plate
Steel plate treated with ferric phosphate
Plate treated with zinc phosphate

10 ²

of the bathroom

pH of the bath

9.02

13th

76.5 70.3

69.1 5.39 ·

8.77 17

59.4
68.4

70.5
5.63 · 10 ²

8.76

17 (I.A.)

81.6
75.9

69.1
4.83-

8.90

10 ²

25th

81.3
79.5

76.3
5.90 · 10 ²

8.70

As can be seen from Table III, the coating compositions to be used according to the invention have a excellent bath stability, and the baths produced with the aid of the present coating composition films with excellent properties even after prolonged standing. In Table III means (I.A.) that cleaning with an ion exchanger was carried out on the 17th day. One lets If the electrodeposition bath is left for a long time, the water-soluble polymers are washed out instead, which lowers the pH of the bath and increases the specific electrical conductivity whereby the formed film has poor properties. In the case it will be in the bathroom removed water-soluble polymers with the help of an ion exchange resin, so that can

<5

Table IV properties

Substrate

cold rolled steel plate

Delte treated with remote zinc phosphate phosphate Steel-steel plate plate

Gloss value
Thickness (μ)
Pencil hardness
Cross cut
Solvent resistance

Xylene

Isopropanol

acetone

Alkali resistance
Acid resistance

85.2 83.2 8i2 28 28 26

FFH 100/100 100/100 100/100

5 °

4-5

4-5

4-5 4-5 4-5

5 4

4-5

4-5

4-5

Example 4

A mixture of the compounds given below was prepared under the same conditions polymerized as in Example 2 and with 17.8 parts / f-Dimethyiaminoäthaao! neutralized, being a Resin solution with a solids content of 57.5%,

Bath again to a bath with a high stability, which provides films with excellent properties, can be regenerated as shown in Table III.

B e i s] p i e 1 3

A mixture of the compounds given below was polymerized under the same conditions as in Example 2 and neutralized with 17.8 parts / I-dimethylaminoethanol, a resin solution having a solids content of 57.2%, an acid number of 19.6 and an ro Gardner viscosity U was obtained.

2-ethylhexyl acrylate 276 parts

Styrene 207 parts

2-hydroxyethyl methacrylate 31.3 parts

N-butoxymethylacryllamide-

Itaconic acid mixture (B) 389 parts

Itaconic acid 6.5 parts

Isopropanol 312 parts

Azobisisobutyronitrile 22.4 parts

2-mercaptoethanol 6 parts

The resin obtained in this way had the following characteristics: Tg = -1.5 ° C., pKa = 8.73, η = 1.15, average molecular weight 9.2 · 10 ³ and α = 0.4. The resin solution was treated in the same manner as in Example 3 to obtain a white pigmented paste. This paste was used to produce a coating bath with a solids concentration of 13%, a pH value of 8.6 and a specific electrical conductivity of 3.57 · 10 ^ ohm / cm " ¹ (with a solids content of 11%) electrodeposition and baking were carried out under the same conditions as in Example 3. The properties of the films obtained are shown in Table IV.

a viscosity Q according to G ard η er and an acid number of 19.9 was obtained.

2-ethylhexyl acrylate

Ethyl acrylate

Styrene

N-Butoxymethylacrylamid (from the mixture obtained according to (D) distilled off and isolated)

Itaconic acid

Azobisisobutyronitrile

2-mercaptoethanol

Isopropanol

234 parts 100 parts 156 parts

157 parts 32.5 parts 22.5 parts 9 parts

539 pieces

The resin obtained had the following characteristics: Tg = -23.5 ° C., pKa = 8.79, η = 1.11, average molecular weight 9.0 · 10 ³ and α = 0.4. The resin solution was treated in the same manner as in Example 2 to obtain a white pigmented paste. This paste was used to produce an electrodeposition bath with a solids concentration of 13%, a pH of 8.70 and a specific electrical conductivity of 2.53 · ΙΟ ² μ ohm ~ 'cm ~ ¹ (at a solids content of 11%) used. The electrical deposition and heating then took place under the same conditions as in Example 2.

In addition, an aqueous solution containing 0.01 mol / liter of L-histidine was prepared and adjusted to the same pH as set the electrodeposition bath. 50 g of this aqueous solution were added to 500 g of des given above coating bath to prepare another deposition bath. The two so made Baths were checked individually with continuous stirring in the open state at 25 ° C. The results are shown in Table V on the basis of the changes in the gloss value and the thickness of the obtained Movies indicated.

40 Table V Duration of the experiment

Without addition

Addition to Beginning

Addition after 20 days

(Days) Shine Thick Shine Thick Shine Thick

0
20th

863
20.0

43
100

85.6
81.1

38 34

86.3 82.5

43 37

(A plate treated with zinc phosphate was used as the test plate.)

The table shows that the bath without dec The addition of L-histidine solution has a much lower stability than the bath with the addition. Farther the stability of the bath, which has already fallen, is improved again by adding L-histidine solution to approximately the original value.

Example 5

In this example a long chain acrylate was used Used together with a short-chain acrylate to prevent the formed film from flowing in the heat * 5 to improve.

A mixture with the following specifiedei Compounds were polymerized under the same conditions as in Example 2 and added with 44.4 parts

1805

(β-Dimethylaminoethanol neutralized, whereby a resin solution with a solids content of 57.7%, a viscosity U according to G ard η er and an acid number of 19.3 was obtained.

Ethyl acrylate 447 parts

Lauryl methacrylate 359 parts

Styrene 520 parts

N-butoxymethylacrylamide

Itaconic acid mixture (B) 965 parts

Itaconic acid 16.5 parts

Azobisisobutyronitrile 59.0 parts

2-mercaptoethanol 22.5 parts

Isopropanol 763 parts

The resin obtained in this way has the following characteristics: Tg = 20 ^° C., pKa = 9.15, η = 1.18, average molecular weight 12.0 · 10 ³ and α = 0.4. The resin was treated in the same manner as in Example 2 to obtain a white pigmented paste. This paste was used to produce an electrodeposition bath with a solids content of 13% and a pH of 8.90 and a specific electrical conductivity of 2.35 · ΙΟ ² μ OhHi ^-1 Cm " ¹ (at a solids content of 11%) Then, electrodeposition and baking were carried out under the same conditions as in Example 2. The properties of the films obtained are shown in Table VI.

007 / If

according to Gardner and an acid number of 10.5 er was holding.

2-ethylhexyl acrylate 340 parts

Styrene 234 parts

N-butoxymethylacrylamide

Itaconic acid acrylonitrile

Mixture (C) 200 parts

Itaconic acid 3 _t 25 parts

Azobisisobutyronitrile 22.5 parts

2-mercaptoethanol 6 parts

Isopropanol 332.3 parts

The resin obtained had the following characteristics 7g = -1.5 ⁰ C, pKa = 8.7, η = 1.19, average molecular weight royal 11 x 10 ^3, and α = 0.4. The resin solution was treated in the same way as in Example 2, a white, pigmented paste being obtained. This paste was used to produce an electrodeposition bath with a solids content of 13%, a pH value of 8.5 and a specific electrical conductivity of 3.13 · ΙΟ ² μ ohm-cm " ¹ (at a solids content of 11% Then, electrodeposition and baking were carried out under the same conditions as in Example 2. The properties of the films obtained are shown in Table VII.

Table VII

Table VI Substrate with ferr —-— 35 properties at Substrate with ferr with zinc phosphate cold phosphal phosphate properties cold behan rolled behan behan rolled delte with zinc stole delte delte stole stole phosphate plate stole stole plate plate behan plate plate delte 40 85.5 stole - ... 39 plate 82 80 85.3 F-H Gloss value 83 30th 32 37 100/100 84.1 45 Thickness (μ) 28 F. F. Gloss value F-H 35 Pencil hardness F. 100/100 100 100 Thickness (μ) 100/100 F-H Cross cut 100/100 Pencil hardness 5 100/100 Resistant to solvents Cross cut 5 speed 5 5 Resistant to solvents 5 5 5 » Xylene 5 5 5 speed 5 5 5 Isopropanol 5 5 5 Xylene 5 5 5 acetone 5 5 5 Isopropanol 5 5 Alkali resistance 5 5 5 acetone 5 5 Acid resistance 5 Alkali resistance 5 Acid resistance game 7

Example 6

This example shows that even when using a mixture of monomers, which with the help of acrylonitrile as azeotropic dehydrating agent was synthesized. Films with excellent properties can be obtained.

A mixture of the compounds given below was polymerized in the same way as in Example 2 and neutralized with 8.9 parts of diethylaminoethanol, a resin solution having a solids content of 59.6% and a viscosity of Y. This example shows that too when using a Monomerengemiscbes aas an acrylamide, of: ™ ^ox ymethylacrylamids a good resin can be obtained for electrical deposition,
To sni 1 _A ^same ° «β8 as according to Example 1, •» kl ^Azobisis ° t «ityronitriU 10 parts of 2-MercaptolrSii"! ^{at 0} ^ BCh of the compounds indicated below were filled.

Ethyl acrylate 693 parts

S ^ ⁰¹ 426 parts

N-Butoxyrnethylaerylamid-

Itaconic acid mixture (A) 486 parts

isopropanol

27 28

The resulting mixture was heated for 2 hours. Ethyl acrylate 50 parts

Here, 5 parts of 2-mercaptoethanol and 3 parts of methyl methacrylate were 50 parts

Azobisisobutyronitrile was added, and the mixture was styrene 395 parts

was kept at 68 ° C. After 2 hours, N-butoxymethylacrylamide became 78.5 parts

3 parts of azobisisobutyronitrile were added, and the er-itaconic acid was 26 parts

warming was continued for another 2 hours. 6 hours azobisisobutyronitrile 22.4 parts

after the beginning the temperature was increased to 75 ° C., 2-mercaptoethanol 6 parts

and the polymerization continued for 2 hours more- isopropanol 372 parts

guided. The resulting solution was made by addition

of 17.8 parts / tf-dimethylaminoethanol neutralized io This resin had the following properties: Tg = ⁰ C. Siert 84, wherein a resin solution having a solids content pKa = 8.60, η = 0.95, average Molekularvon 54.3% , a viscosity R according to Gardner and weight 14 · 10 ³ and α = 0.4. The resin solution had an acid number of 9.8. The resin treated in the same way as in Example 2 had the following characteristics: Tg = 17.5 ^° C., pKa = 9.0, a white, pigmented paste being obtained, η = 0.88, average molecular weight 15. This paste was obtained for making an electrical 9.8 · 10 ³ and a - 0.4. The resin solution was treated in the deposition bath having a solid content in the same manner as in Example 2 to give 13%, pH 8.8, and more specifically, a white pigmented paste. This electrical conductivity of 4.9 · ΙΟ ² μ ohms "'cm" ¹ paste was used to produce an electrical deposit (with a solids content of 11%) a pH of 8.55 and a specific electrical heating carried out under the same conditions as the tric conductivity of 2.50 · ΙΟ ¹ μ ohm "'cm" ¹ in Example 2. The properties of the he (with a solids content of 11%). Persistent films are given in Table 9, but the final electrodeposition and films were not smooth and had less annealing under the same conditions as 25 throws,
carried out in example 2. The properties of the films obtained are given in Table VIII. _, ", ..,

Table IX

Table VIII Substrate Solvent independent
wedge 4th
5
5 with ferr with zinc 30th properties Substrate at 4th with ferr with zinc cold Xylene
Isopropanol
acetone 5 phosphate phosphate cold 4th phosphate
behan phosphate
behan rolled Alkali resistance 5 4 behan
delte behan
delte rolled
stole 4th
1
1 delte delte properties stole
plate Acid resistance Example 8 stole stole plate stole stole plate plate game 9 plate plate 35 A mixture of the below 85.6
26th
H 83.5
26th
H 28 29 84.5
22nd
H 100 100 100 100 Gloss value 30th 75
6H 56
6H 100 100 Thickness (μ) 70
Pencil hardness 6 H
Solvent-compatible
speed 4th 4th 4th
4th
5 4th
5
5 4U Xylene
Isopropanol 4th 4th Gloss value
Thickness (μ)
Pencil hardness 5 5 45 acetone
Alkali resistance
Acid-resistant wedge 4th
1
J 4th
1
1
1 Cross cut 5 4 5 A 50 specified ver 55

This example shows that when a resin having a very high Tg (glass transition temperature) is used, an excellent film cannot be obtained.

A mixture of the compounds given below was polymerized according to Example 2 and neutralized with 14.2 parts of ^ '- dimethylaminoethanol. 65 a resin solution with a solids content of 56.5%, a viscosity Z according to G a r d η e r and an acid number of 19.3 was obtained.

neutralized with 44.4 parts / - dimethylaroinoethanol

wherein a resin solution having a solids content of voi

56.8% and an acid number of 19.5 was obtained

2-ethylhexyl acrylate 806 parts

Styrene "520 parts

N-butoxymethylacrylamide 400 parts

o-methyl glutaric acid 90 parts

Azobisisobutyronitrile 59 parts

2-mercaptoethanol 2Z5 parts

Isopropanol 753 parts

The resin obtained had the following characteristics: 7g = -8.0 ⁰ C, pKa = 9.25, η = 1.15, average molecular weight 10.5 · ΙΟ ^3, α = 0.4. This resin was treated in the same manner as in Example 2 to obtain a white pigmented paste. This paste was then used to produce an electrodeposition bath with a solids content of 13%, a pH of 9.0 and a specific electrical conductivity of 2.1 3 ■ ΙΟ ² μΟΙιΐΏ-'αη- ¹ (with a solids content of 11% ) used. The subsequent electrodeposition and baking were carried out under the same conditions as in Example 2. The properties of the films obtained are given in Table X. It can be seen from the results in the table that when α-methyleneglutaric acid is used, films having practically the same properties as when itaconic acid are used are obtained.

Table X

properties

Substrate

cold rolled steel plate

steel plate treated with ferric phosphate

zinc phosphate treated steel plate

Gloss value 85.5 84.7 83.8

Thickness (μ) 40 39 39

Pencil hardness F-H F-H F-H

Cross cut 100 100 100/100 100 100 Solvent resistance

Xylene 5 5 5

Isopropanol 5 5 5

Acetone 5 5 5

Alkali resistance 5 5 5

Acid resistance 5 5 5

Table XI

properties

Substrate

with ferric phosphate
treated
steel plate

treated with zinc phosphate
steel plate

Gloss value

Thickness (μ)

Pencil hardness

Cross cut

Solvent resistance

Xylene

Isopropanol

acetone

Alkali resistance
Acid resistance
Salt spray test

80.0 76.8

34 36

F F

100/100 100/100

5
5
5
5
5
4.5 mm

5
5
5
5
5
1.5 mm

A comparison with the result of the salt spray test in Table II shows that Acrylhar7 coating compositions, containing epoxy resins improve the corrosion resistance of the films obtained.

Example 11

10 parts of water-soluble melamine resin were added to 100 parts of the resin solution obtained in Example 3. This mixed resin solution was treated in the same manner as in Example 2 to obtain a white pigmented paste. This paste was used to produce a coating bath with a solids content of 13 percent by weight, a pH value of 8.9 and a specific electrical conductivity of 3.15 · ΙΟ ² μ Ohm ^ cm " ¹ (for a solid

material content of 11 percent by weight) is used.

Then electrodeposition and bakeout were performed under the same conditions carried out as in Example 2. The properties of the films obtained are given in Table XII.

Table XIl Example 10

To 375 parts of the white pigmented paste according to Example 2 were 30 parts of an epoxy resin with a melting point of 64 to 74 C. An epoxy equivalent of 450 to 500 and a molecular weight of about 900 (condensation product of bisphenol A and polyethylene glycol in the form of 50 ° Oigen solution in ethylene glycol monobutyl ether). After grinding, the mixture was used to prepare an electrodeposition bath with a solids concentration of 13.2%, a pH of 8.66 and a specific electrical conductivity of 3.02 · ΙΟ ² μ ohms " ¹ Cm" ¹ (at a Solids content of 11%) is used. Using the electrodeposition bath thus prepared, a ferrous phosphate treated steel plate and a zinc phosphate treated steel plate were electrodeposited at A) V for 3 minutes. The films obtained were then baked at 180 ° C. for 30 minutes. The properties of the films are given in Table XI.

properties Substrate wit fine with Zinfc cold phosphate phosphate rolled cultivated behan stole ddte delte plate stole Stole- plate plans 84.7 83.3 Gloss value 84.5 32 28 Thickness (μ) 32 H-2H H-2H Pencil hardness H-2H 300/100 100/100 60 cross cut J 00/100 Solvent resistant
speed 5 5 Xylene 5 5 5 . Isopropanol 5 5 5 acetone 5 5 5 Alkali resistance 5 5 5 Acid resistance 5

Example 12

Electric plating baths were prepared in the same manner as in Example 2 except that the amount of 2-mercaptoethanol used to modify molecular weight was varied as shown in Table XIII. Using the coating baths produced in this way, cold-rolled steel plates were exposed to electric light at 80 V for 3 minutes. The films obtained were then heated at 180 ^° C. for 30 minutes. The characteristics of the fun »are given in Table XIII.

Table XIII

and has inferior bath stability; the received The film runs worse in the heat.

Example 13

2 g each of the pigments given in Table XIV were dispersed individually in 100 g of water. The dispersions were adjusted to the pH values given in Table XIV. After 3 hours, the precipitated Volume quantities of the pigments were determined, and the pKp values of the pigments were determined according to the relationship given in column 17, lines 1 to 10 calculated.

15 Table XIV

Added amount of 2-mercaptoethanol (based on Monomer mixture)

1.25% 0.83% 0.42%

pH of the Dispersion

pigment

1.0 ₃

RuB

20th red Iron oxide

pKa 9.20 9.13 9.05 2.0 98 10 95 3.0 98 10 95 η 1.17 1.08 1.92 4.0 98 10 95 α 0.4 0.4 0.4 ² S 5.0 10 10 95 6.0 10 10 15th shine 7.0 10 10 15th [I] 81.7 79.1 63.2 8.0 10 97 15th [Π] 68.9 75.3 49.5 3 ° 9.0 95 97 15th Molecular weight 9910 9800 14 730 10.0
11.0 96
98 97
97 95
97 12.0 98 97 97 In the table is the < Gloss [I] the gloss value of the 35 pKp 8.6 7.8 9.6

While gloss [II] is the gloss value of the film film which has been electrically deposited immediately after preparation of the bath, which was electrodeposited 7 days after preparation by continuous stirring of the bath at 40 ⁰ C.

The results of Table XI11 show that the pKa and η of the polymers differ from each other depending on the molecular weight, although the monomers composing the polymers are the same; the stability of the electrodeposition baths produced therefrom and the gloss of the films obtained are thereby greatly influenced. Furthermore one recognizes. that especially when a high molecular weight polymer is used, a film with an excellent gloss cannot be obtained because the resin has a low pKa value, a high n value Enamel that has excreted after being dispersed in water at a certain pH and after allowing the dispersion to stand for a certain period of time. The larger this value, the better the dispersibility in water.

Pigmented pastes were obtained by treating pigments with the pKp values given in Table XV with resins with pKa values of 8.3: and 9.06 in the same way as in Example '. manufactured. These pastes were used to make coating baths. The dispersion stability of the pigmented baths thus prepared was measured, and the results given in Table XV were obtained.

Table XV ? Kp value Separated volume after 3 hours pKa value pKp value Secluded pKa value of the pigment 55.5 of the resin of the pigment volume of the resin after 1.5 hours 50.5 9.70 72.5 11.0 9.06 9.70 96 8.33 9.05 71.5 10.0 9.06 9.53 73 8.33 8.60 22.0 11.0 9.06 9.45 61 8.33 8.30 10.0 99.0 9.06 8.95 52 8.33 7.75 33.0 9.06 8.60 52 8.33 6.73 99.0 9.06 7.75 54 8.33 9.06 6.73 84

The results of Table X V show that by combining a pigment and a resin, the meet the condition jpKp - pKpj ^ 0,1, obtained Coating bath recorded water dispersibility of pigment particles and excellent Has dispersion stability

Example 14

Resins with pKa values of 8.33 and 9.06 prepared according to Example 2 and with ^ -Dimethyl- ίο aminoethanol neutralized to an apparent degree of neutralization of 0.45. To manufacture the Resins were polymerized in the two mixtures given below.

Mixture of the resin having a pKa of 8.33 ^'5

Ethyl Acrylate 247 parts

Styrene 153 parts

N-butoxymethyl acrylamide 100 parts

2-mcrcaptoathaiiol 5.8 parts

Azobisisobutyronitrile 22.4 parts

Itaconic acid 24.8 parts

Isopropanol 447 parts

Mixture for the resin with a pKa value of 9.06 «

Ethyl Acrylate 271 parts

Styrene 166 parts

N-butoxymethylacrylamide 100 parts

Itaconic acid 10 parts

2-mercaptoethanol 5.8 parts

Azobisisobutyronitrile 20 parts

Isopropanol 427 parts

Baked at 180 ° C for 30 minutes. The properties the films are given in Table XVI.

Table XVI Properties Colored enamel

grey black

Substrate

cold- with zinc- cold- with zinc rolled phosphate rolled phosphate Steel treated Reinforced concrete slab delte slatte delte Plate plate

The resin with the pKa value of 8.33 had the following characteristics: η = 0.9, Tg = 16 ⁰ C, average molecular weight 9000. The resin with the pKa value of 9.06 had the following characteristics: η = 1, 4, Tg = 20 ^c C, average molecular weight 12,000.

The resin obtained according to Example 2 with a pKa value of 9.20, titanium oxide with a pKp value of 9.53 and carbon black with a pKp of at least 10 were used to produce gray in the following manner or black pigmented baths are used:

Gray pigmented bathroom

_{55 parts of TiO 2} and 1.5 parts of carbon black were added to 100 parts of resin solution. The mixture was ground in a ball mill for 24 hours and then a further 200 parts of resin solution were added, a gray-pigmented paste being obtained. This paste was used to make a coating bath with a concentration of 13% and a pH of 8.75.

Black pigmented bath

55

To 100 parts of the resin solution, 5.1 parts of carbon black was added. The mixture was in one for 24 hours Ground ball mill and then mixed again with 200 parts of resin solution, one pigmented black Paste was obtained. This paste was used to make a coating bath with a concentration of 11.8% and a pH of 8.8 was used.

Using the baths given above, cold rolled steel plates and zinc phosphate treated panels were electroplated for 2 minutes at 8 V and the resulting films were

shine 75.1 71.8 87.2 86.6 Thickness (μ) 36 32 49 36 Pencil hardness HB HB 3B 2 B Cross cut 100/100 100/100 100/100 100 100 solvent resistance Xylene 4-5 4-5 5 4-5 Isopropanol 5 4-5 4-5 4-5 acetone 5 5 4-5 4-5 alkali 5 5 5 5 resistance acid 5 5 5 5 resistance

The results of Table XVI show that the coating compositions according to the invention also with colored coatings provide excellent films in one layer.

The stabilities of the coating baths given above are given in Table XVII, taking into account the gloss values of the films are given.

Table XV11 Colored E-mail black with zinc
phosphate
treated
plate Days Gray 86.6 Substrate cold rolled
steel plate 83.5 cold
rolled
stole
plate with zinc
phosphate
treated
plate 87.2 83.6 75.1 71.8 91.1 0 76.1 73.1 88.4 10 76.5 71.0 22nd

The results of Table XVII show that the colored enamel coating baths according to the invention have excellent stability and always give good films.

Comparative example 1

A mixture of the compounds listed below was polymerized in the same manner as in Example 1 to obtain a resin solution became.

2-ethylhexyl acrylate. 157 pieces

Ethylacrylal 155 parts

Styrene 146 parts

N-butoxymethylacrylamide ....... 118 parts

Acrylic acid 22TeHe

Azobisisobutyronitru 22.4 parts

2-mercaptoethanol 6 * file

Isopropanol 474 parts

The resin solution was neutralized with 16 parts of / i-dimethylaminoethanol, whereby a resin was obtained with the following characteristics: pKa = 8.57 η = 1.10, α = 0.6, and Tg = -3.0 ⁰ C. The resin solution had a solids content of 54.0%, an acid number of 11.8 and a viscosity T according to Gardner. A white pigmented paste was prepared from this resin solution in the same manner as in Example 2. This enamel paste was used to prepare an electrodeposition bath with a solids content of 13%, a pH of 8.4 and a specific electrical conductivity of 4.85. ΙΟ ² μ OhIn ^-1 Cm " ¹ (with a solids content of 11%) was used. The electrodeposition was then carried out under the same conditions as in Example 2, and the films obtained were baked for 30 minutes at 180 ^° C. The properties of Films thus obtained are shown in Table XVIII.

Table XVIt 1 Substrate with ferr with zinc properties cold phosphate phosphate rolled behan behan stole delte delte plate stole stole plate plate 35 77.6 67.3 78.0 27 27 shine 28 H H ⁴ Thickness (μ) H 100/100 100/100 Pencil hardness 100/100 Cross cut Resistant to solvents 4th 3 « speed 3 5 5 Xylene 4th 5 4th Isopropanol 4-5 5 4th acetone 5 4th 4 ⁵⁰ Alkali resistance 5 Acid resistance 13.2 43.1 Bath stability test 18.7 7.0 32.0 Gloss value on the 2nd day 14.3 Gloss value on the 7th day

In the table, the properties other than the bath stability are the same as in Example 2. The bath stability is represented by the gloss value of a film formed by continuously stirring the bath in the open state at 25 ° C. and electrodeposing the film while stirring . The results of Table XVIII show that, when acrylic acid is used, the resin obtained has favorable pKa and n values, but that its stability drops markedly over time. This means that a polymer obtained using acrylic acid as the acidic component is a polymer mixture with different pKa values, polymers with low pKa values gradually migrating into the aqueous phase.

Comparative example 2

A coating material for electrical deposition was produced from a polymer which was obtained in that an amide polymer using acrylic acid as α, / ϊ-ethylenic unsaturated fatty acid was formed, whereupon the amide group N-butoxymetbylated with formaldehyde and butanol was. The properties of the coating material and after electrodeposition are given in table ΧΓΧ.

Half of a mixture of the compounds listed below was placed in the same jar Filled as in Example 1, and the polymerization was started at the boiling point of the mixture. The remainder of the mixture was added dropwise over 3 hours and polymerized.

Acrylic acid 64 parts

Acrylamide 120 parts

Styrene 200 parts

Ethyl acrylate 216 parts

Butyl acrylate 200 parts

Butanol 560 parts

di-tert-butyl peroxide 8 parts

tert-dodecyl mercaptan 40 parts

To the polymer solution obtained, 121.5 parts of paraformaldehyde was added and the mixture was added dehydrated under reflux until the water was completely removed. The amount of water removed was 59.4 ml.

The resin solution thus obtained was added with TiO ₂ and treated in the same manner as in Example 2, using an electric plating bath having a solids concentration of about 10%, a pH of 8.58. a specific electrical conductivity of 6.17 ² μ ohm "'cm" ^l , a pKa value of 8.53. an η value of 0.74 and an α value of 0.4.

That har? according to the invention, which was obtained using itaconic acid as the acidic component, ie the resin according to Example 2, had a pKa value of 9.20 and an η value of 1.17 and produced a coating bath with a specific electrical conductivity of 2.24 ■ ΙΟ ² μ Ohm ~ 'cm ~ ^l . Taking these values into account, it could be expected that the bath stability of a coating bath with a polymer using acrylic acid as the acidic component would result in films with poorer properties. This is attributed to the fact that acrylic acid, when used as the acidic component, interpolymerizes poorly with the other monomers and provides a polymer mixture with different values for pKa and η, so that polymers with a low pKa value get into the aqueous medium and the stability of the bath coating deteriorate.

Using the coating bath thus prepared, a cold-rolled steel plate (abbreviated Fe), one plate treated with zinc phosphate (abbreviated as P-Zn) and one treated with ferric phosphate

% 0

Plate (abbreviated P-Fe) each of the following treatments subject to:

A. Coated for 3 minutes at 60 V and cured for ^{30 minutes at 160 9 C,}

B. coated for 3 minutes at SO V and cured for 30 minutes at 180 ° C,

C. Coated at 100 V for 3 minutes and 30 minutes

cured at 180 ° C.

The properties of the obtained films are in Table XIX given. P-Fe P-Zn B. P-Fe P-Zn C. P-Fe P-Zn Table XDC 70.7 60.9 55.5 55.0 49.4 49.7 properties Coating and hardening conditions 34 33 Fe 45 36 Fe 53.5 45 A. 2H 2H 50.5 - - 36.9 2H 2H Substrate 100/100 100/100 44.5 - 65 100/100 100/100 Fe - 2H shine 67.7 - 100/100 Thickness (μ) 37 4-5 5 - - 4-5 4 5 Pencil hardness 2H 4-5 4-5 __ 4-5 4-5 Cross cut 100/100 5 4-5 . - _. - 4 5 4th 4th Resistant to solvents 2 2 - -2 - 4-5 2 2 speed 4th 4th - - - 4th 4th 5-4 Xylene 4-5 - ■ - - 6th 7th 2 - - Isopropanol 4-5 - - 20th 30th 5-4 - - acetone 5 15th - Alkali resistance 2 20th - Acid resistance 4th Erichsenwert - Impact resistance -

The results of Table XDC show that films made from the coating material of the comparative example a slightly poorer gloss and a low Erichsen value as well as a lower impact resistance have as films that are produced with the aid of the present coating composition.

Also in Table XX is the stability of the above specified coating bath, taking into account the gloss values of the films specified, the 3 minutes at 60 V and cured for 30 minutes at 180 ° C.

Table XX Substrate with ferr with zinc pH Specific Days phosphate phosphate value electrical cold behan behan conductivity rolled delte delte stole plate plate plate 70.7 60.9 21.6 19.3 (μΟΙιπι'Όη ") 67.7 28.0 22.0. 8.58 6.17 ² 0 17.9 8.80 6.630 · 10 ² 1 21.0 8.62 7.695 · 10 ² 3

The results of Table XX show that a coating material made using acrylic acid was obtained as the acidic component, has an extremely low bath stability and not as Deposition material with practically useful properties can be used, which can be converted into a Layer can be applied.

Comparative example 3

A mixture of the compounds shown below was prepared in the same manner as in Example 2 to obtain a resin solution

Acrylamide 25 parts

Methacrylic acid 25 parts

Butyl acrylate 125 parts

Styrene 75 parts

Butanol 270 parts

di-tert-butyl peroxide 3.8 parts

tert-dodecyl mercaptan 2.5 parts

50,450 parts of the resin solution were mixed with 22.5 parts Paraformaldehyde and 2.25 parts of triethylamine were added and to introduce de? N-methylol group heated under reflux in the amide copolymer.

The resin solution was then treated in the same manner as in Example 2 to obtain a pigmented paste. This paste was used to produce an electrical deposition bath with the following characteristics: pKa = 8.61, η = 0.42, ο = 0.4, pH = 9.1, specific electrical conductivity = 7.43 · 10 ² μ Ohm " ¹ cm" ¹ . Using the bath produced in this way, a cold-rolled steel plate, a zinc phosphate-treated plate and a ferric phosphate-treated plate were each electrically coated individually for 3 minutes at 66 V, and the films obtained were baked at 175 ° C. for 30 minutes. The properties of the films so obtained are given in Table XXI.

Table XXI

Comparative example 5

properties

Substrate

cold- with long-distance- with zinc-rolled phosphate phosphate Pedestal treatment plate

Mixtures D-Ϊ and D-2, each having the following specified compounds were treated in the same way as in Example 2, whereby resin solutions were obtained:

ddte plate

3rd plate

Gloss 1.0 1.4 1.0

Thickness (μ) 60 60 50

Pencil hardness HFH

Cross cut 20/100 100/100 100 / l

Solvent resistance

Xylene 5 2 3

Isopropanol 5 2 4–5

Acetone 3 1 1

Alkali resistance 3 3 3

Acid resistance 3 3 3

10

The results of Table XXI show that the electrical coating material according to this comparative example has no practical value and as a coating material is not suitable for single-layer coatings.

Comparative example 4

35 TUE

Ethyl acrylate 250 parts

Styrene 143 parts

N-butoxymethylacrylamide 286 parts

Itaconic acid 29.3 parts

Isopropanol 269 parts

Azobisisobutyronitrile 22.4 parts

2-mercaptoethanol 6.0 parts

D-2

Ethyl acrylate 693 parts

Styrene 426 parts

N-butoxymethylacrylamide

Itaconic acid mixture (A) 486 parts

Isopropanol 80OTeUe

Azobisisobutyronitrile 56 parts

2-mercaptoethanol 15 parts

The resin solutions were used to prepare electrodeposition baths in the same manner as used in example 2. The physical constants of the resins and the deposition baths are given in Table XXII.

A mixture of the compounds shown below was prepared in the same manner as in Example Table XXII

game 2, with an electrical deposition 40

bad with the following characteristics: pKa = 6.84, η = 2.21, a = 0.4, pH = 6.52, specific electrical conductivity = 1.28 · Hare DI

D-2

45

Ethyl acrylate 425 parts

Acrylamide 25 parts Itaconic acid 50 parts Azobisisobutyronitrile 22.4 parts

2-mercaptoethanol 6 parts

Isopropanol 472 parts

55

Using the bath thus prepared was- to coating the treated plate and a cold rolled steel plate, a rail zinc phosphate a treated Ferripbosphai plate electrically, said Fume a gloss value of 863, 28.0 and 833, a thickness of 47, 343 or .47 μ ham «. However, since the resin in the bath was a thermoplastic resin, a film having practically useful properties could not be obtained in 6s.

pKa 7.75 9.06 π 1.67 0.82 α 0.35 0.4 Acid number 723 19.0 Electro 1260 6750 chemical equivalent to Specific 934 1.96 electrical if \ 2. fXL .ι. τ. - 1
1 \ T (i. V / tHB cm It; p. Ohm cm Conductive wedge of the bathroom PH value 739 8.80 of the bathroom Day 22 ⁰ C 15 ° C

Been using these plating baths cold rolled steel plates, treated with femphosphate and zinc phosphate treated Plates coated to form films. The properties of the film are given in Table XXIII.

509537/397

Table XXIII

il

42

properties

resin

D-I

Substrate

cold rolled steel plate

Gloss 48.2

Thickness (μ) 75

Pencil hardness F

Cross cut 100/100 solvent resistance

Xylene 3

Isopropanol 4

Acetone 2

Alkali resistance 4

Acid resistance 5

Film surface rough

plate treated with zinc phosphate

10.3 30 F 100/100

3 4 2 4 5 rough

plate treated with ferric phosphate

13.2 71 F 100/100

3 4 2 4 5 rough D-2

cold rolled
steel plate

with zinc phosphate
treated
plate

92.8
36
H
100/100

4-5

smooth

91.3
35
H
100/100

3
3
4th
5
4th
applies

plate treated with ferric phosphate

90.8 38 H 100/100

3 4 5 5 4 smooth

In this comparative example, the resin D-I, in which the proportion of the acidic copolymer component was increased to increase the acid number of the polymer, and the resin D-2 according to Invention, in which the proportion of the acidic copolymer component was kept low, for investigation the properties of the resin and the influence of the resins on the electrodeposited Films used. Tables XXII and XXIII show that the acid number of the resin increases too lead to a decrease in the pKa value and an increase in the n value of the resin, whereby the specific electrical conductivity of the coating bath produced therefrom increases and an electrical one deposited film with greater thickness and lower smoothness or lower gloss obtained will. As a result, if the acid value of the resin used increases, it is impossible to obtain a To obtain coating material for electrodeposition, the al? single layer can be applied can.

Comparative example 6

TerpolyBaere an itaconic acid, 2-Hydroxyäthyiniethacryiat aod ÄthyJacrylat was obtained in a manner similar to that of Example 1. The pK values of these polymers are given m Table XXIV.

Table XXIV Mole percent

ItacoAs acrylai

55

Mojprozenl
Atbytacrytate Molen broke
Itaconsaeans » pKa + 2-Hydro *:
ethyl meth-
acrylate) 90
90
90 0.5
0.2 6J25
7.05
7.80

Mole percent
itaconic acid
+ 2-hydroxyethyl methacrylate

Mole percent
Ethyl acrylate

Breakwater

uric acid/

(Itaconic acid

+ 2-hydroxy-

ethyl meth-

acrylate)

pKa

80
80

80
_.

⁷ O
70

0.5

0.25

01

0.17
0.06

6.50 7.05 7 80

^ö ' ^{/ ü} 6.50

6.70

It can be seen that the pKa values with the Change content of hydrophilic functional groups

Comparative example 7

^{A Manufacture of} the monomer mixture

The following substances were mixed with each other να:

N-butoxymethylacrylamide 294 g

Ethyl acrylate 4QQg

Methyl methacrylate 359 g

This mixture was washed with

a) 11 5% aqueous NaOH solution,

b) 1 1 water.

After washing, 1000g of mono- ^{oaere were left behind} which were added:

1. Methacrylic acid 177 ",

H. Lauryl mercaptan '.'. '.'. '.'. '.'. '.'. '. 6s

An inhibitor-free monomer mixture was obtained in this way

B. Preparation of a catalyst emulsifier solution

Polyoxyethylene sodium alkyl S

sulfonate 30 g

Ammonium persulfate 5 g

Water 1285 g

These substances were mixed together to produce a catalyst emulsifier solution.

In one equipped with a stirrer, reflux condenser, thermometer, temperature regulator and two dropping funnels Glass vessel was filled with 1315 g of water. After heating to 50 ° C., 50 ml of monomer mixture were added and catalyst emulsifier solution added. Then the temperature was increased to 90 ° C, whereupon the remainder of the monomer mixture and the catalyst emulsifier solution was added dropwise over a period of 2 to 2½ hours.

After the addition of components A and B had ended, the emulsion obtained was ^{kept at 90 °} C. for a further 1.5 hours and flushed with nitrogen for 10 minutes in order to remove traces of unreacted monomers. Then the emulsion was cooled.

The emulsion was made with 0-dimethylaminoethanol neutralized and diluted to a solids content of 13 percent by weight, whereupon the parameters pKa (= 7.1) and π (= 1.9) were determined.

Comparative example 8

In a vessel equipped with stirrer, thermometer and reflux condenser was charged a mixture of 174 parts of butanol and 348 parts of butyl glycol was charged and heated to 125 to 130 ⁰ C. Then the mixtures indicated below were added dropwise in a ratio of about 3: 1 while maintaining the indicated temperature.

Mixture I.

Methacrylic acid 136 parts

Styrene 136 parts

Acrylamide 72 parts

Ethyl acrylate 136 parts

Butyl acrylate 200 parts

Mixture II

Butyl glycol 105 parts

Lauryl mercaptan 18 parts

tert-butyl peroxide 9 parts

Butanol 53 parts

The mixture was then heated at 130 ° C for about 2 to 3 hours until the solids content of the solution reached about 50%. The resin solution obtained was made to have a solids content of 13 percent by weight diluted, whereupon the parameters pKa (= 6.5) and η (= 2.1) were determined.

Claims (1)

Patent claims: 1. Use eipes by ammonia or Amine bases from partially neutralized copolymer resin A. 93.5 to 35 mole percent of a component consisting of at least one compound with the general formula